Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
DIR = [(1, 0), (-1, 0), (0, 1), (0, -1)]

H, W = [int(x) for x in input().split()]
G = []
B = 0

G.append('#' * (W + 2))
for i in range(H):
    s = input()
    B += s.count('.')
    G.append(['#'] + list(s) + ['#'])
G.append('#' * (W + 2))

que = [(1, 1, 1)]
ans = -1

while que:
    y, x, c = que.pop(0)
    if (y, x) == (H, W):
        ans = c
        break
    for dir in DIR:
        ny = y + dir[0]
        nx = x + dir[1]
        if G[ny][nx] == '.':
            G[ny][nx] = '#'
            que.append((ny, nx, c + 1))

print(B - ans if ans != -1 else -1)